1. Field of the Invention
The present invention relates to a method of forming a patterned thin film, and to a method of forming a magnetic pole of a thin-film magnetic head by using the method of forming a patterned thin film.
2. Description of the Related Art
Performance improvements in thin-film magnetic heads have been sought as areal recording density of hard disk drives has increased. Such thin-film magnetic heads include composite thin-film magnetic heads that have been widely used. A composite head is made of a layered structure including a write (recording) head having an induction-type electromagnetic transducer for writing and a read (reproducing) head having a magnetoresistive (MR) element for reading.
The write head comprises a bottom pole layer, a top pole layer, a write gap layer, and a thin-film coil. The bottom and top pole layers include pole portions that are opposed to each other and placed in regions on a side of an air bearing surface. The write gap layer is provided between the pole portion of the bottom pole layer and the pole portion of the top pole layer. The thin-film coil is arranged such that at least a part thereof is insulated from the bottom pole layer and the top pole layer.
It is required to increase the track density on a magnetic recording medium in order to increase recording density among the performance characteristics of a write head. To achieve this, it is required to implement a write head of a narrow track structure wherein the width of the pole portions of the bottom and top pole layers on a side of the air bearing surface, that is a write track width, is reduced down to microns or the order of submicron. Semiconductor process techniques are utilized to implement such a structure.
As disclosed in Published Unexamined Japanese Patent Application (KOKAI) No. Hei 7-262519, for example, frame plating may be used as a method of fabricating magnetic poles that define the track width. In this method, an electrode film is formed on a base, and a resist layer is formed on the electrode film. The resist layer is patterned through a photolithography process to form a frame to be used for plating. Then, this frame is used to perform plating with the previously formed electrode film as a seed layer. A patterned plating layer is thereby formed.
As described above, it is desired to achieve a thin-film magnetic head having a write head with a small track width. Therefore, in forming magnetic poles by frame plating, the widths of the magnetic poles are reduced by means of sophisticated resists, shorter wavelengths of exposure light, and the like.
According to the prior-art method of frame plating, however, because the resist layer is patterned using optical measures and the frame thereby obtained is used to form the patterned plating layer, it is theoretically impossible to form a patterned plating layer finer than the dimensions determined by optical limitations. Consequently, it is also impossible, by means of the frame plating, to form a magnetic pole finer than the dimensions determined by optical limitations.
As disclosed in Published Unexamined Japanese Patent Application (KOKAI) No. 2000-20914, the present inventor has proposed a technique for forming a fine metal film. This technique comprises the steps of: forming a first resist frame in a pattern corresponding to that of the metal film to be formed, on a base having conductivity at least across its surface; attaching a metal plating film to around this first resist frame by electro-plating; removing the first resist frame while leaving the metal plating film unremoved; and forming the metal film inside a groove in a patterned layer obtained through the removal of the first resist frame.
According to the above-described technique, when the metal film is to be formed through plating, a second resist frame is desirably formed to cover the patterned layer obtained through the removal of the first resist frame, before the formation of the metal film. The reason is that the patterned layer obtained through the removal of the first resist frame is made of metal and therefore, without the second resist frame, the metal film can be formed not only inside the groove in the patterned layer but also over the patterned layer.
Thus, the above-described technique necessitates the frame of two-layered structure when forming the metal film by plating, which results in an increase in the number of steps required for the metal film formation. The technique is therefore susceptible of improvement.
It is an object of the invention to provide a method of forming a patterned thin film capable of forming patterned thin films finer than the dimensions determined by optical limitations, and a method of forming a magnetic pole of a thin-film magnetic head capable of forming magnetic poles finer than the dimensions determined by optical limitations, through the use of the method of forming a patterned thin film.
A method of forming a patterned thin film according to the invention is provided for forming a patterned thin film by using a frame, and comprises the steps of: forming a convex first patterned layer made of a first material on a conductive base; forming a second patterned layer to be a frame on the base around the first patterned layer, the second patterned layer being made of a nonconductive second material that is different from the first material; making the second patterned layer into the frame by removing the first patterned layer, the frame having a groove formed by the removal of the first patterned layer; and forming a patterned thin film in the groove of the frame.
According to the method of forming a patterned thin film of the invention, it is possible to form the groove of the frame finely by forming the convex first patterned layer finely. The method therefore allows a fine formation of the patterned thin film in the groove.
In the method of forming a patterned thin film of the invention, plating may be used in the step of forming the patterned thin film.
In the method of forming a patterned thin film of the invention, the step of forming the second patterned layer may include the steps of: forming a covering film made of the second material so as to cover the first patterned layer; and making the covering film into the second patterned layer by removing an upper part of the covering film so that a top surface of the first patterned layer is exposed.
In the method of forming a patterned thin film of the invention, the step of forming the first patterned layer may include the steps of: forming a convex pattern layer that is made of the first material and has a shape greater than a desired shape of the first patterned layer; and making the convex pattern layer into the first patterned layer by removing part of the convex pattern layer.
In the method of forming a patterned thin film of the invention, the first material and/or the second material may be a resist.
A method of forming a magnetic pole of a thin-film magnetic head according to the invention is provided for forming a layer including a pole portion of a thin-film magnetic head, the thin-film magnetic head comprising: a medium facing surface that faces toward a recording medium; a first magnetic layer and a second magnetic layer magnetically coupled to each other and including pole portions that are opposed to each other and placed in regions of the magnetic layers on a side of the medium facing surface, each of the magnetic layers including at least one layer; a gap layer provided between the pole portions of the first and second magnetic layers; and a thin-film coil at least a part of which is placed between the first and second magnetic layers and insulated from the first and second magnetic layers. The method comprises the steps of: forming a convex first patterned layer made of a first material on a conductive base; forming a second patterned layer to be a frame on the base around the first patterned layer, the second patterned layer being made of a nonconductive second material that is different from the first material; making the second patterned layer into the frame by removing the first patterned layer, the frame having a groove formed by the removal of the first patterned layer; and forming a layer including one of the pole portions in the groove of the frame, the layer being made of a magnetic material.
According to the method of forming a magnetic pole of a thin-film magnetic head of the invention, it is possible to form the groove of the frame finely by forming the convex first patterned layer finely. The method therefore allows a fine formation of the layer including one of the pole portions in the groove.
In the method of forming a magnetic pole of a thin-film magnetic head of the invention, plating may be used in the step of forming the layer including one of the pole portions.
In the method of forming a magnetic pole of a thin-film magnetic head of the invention, the step of forming the second patterned layer may include the steps of: forming a covering film made of the second material so as to cover the first patterned layer; and making the covering film into the second patterned layer by removing an upper part of the covering film so that a top surface of the first patterned layer is exposed.
In the method of forming a magnetic pole of a thin-film magnetic head of the invention, the step of forming the first patterned layer may include the steps of: forming a convex pattern layer that is made of the first material and has a shape greater than a desired shape of the first patterned layer; and making the convex pattern layer into the first patterned layer by removing part of the convex pattern layer.
In the method of forming a magnetic pole of a thin-film magnetic head of the invention, the first material and/or the second material may be a resist.
In the method of forming a magnetic pole of a thin-film magnetic head of the invention, the layer including one of the pole portions may be a layer that defines a track width.
Other and further objects, features and advantages of the invention will appear more fully from the following description.